Sindhalso spelled Sindprovince of southeastern Pakistan. It is bordered by the provinces of Balochistān on the west and north, Punjab on the northeast, the Indian states of Rajasthan and Gujarat to the east, and the Arabian Sea to the south. Sindh is essentially part of the Indus River delta and has derived its name from that river, which is known in Pakistan as the Sindhu. The province of Sindh was established in 1970. The provincial capital, Karāchi, is situated on the southwestern coast. Area 54,407 square miles (140,914 square km). Pop. (2006 est.) 35,864,000.

The area of present-day Sindh province was the centre of the ancient Indus valley civilization, as represented by the sites of Mohenjo-daro, Amre, and Kot Diji. This early civilization existed from about 2300 to 1750 BCE. There is then a gap of more than a millennium before the historical record is renewed with Sindh’s annexation to the (Persian) Achaemenid empire under Darius I in the late 6th century BCE. Nearly two centuries later, Alexander the Great conquered the region in 326 and 325 BCE. After his death, Sindh came under the domination of the empires of Seleucus I Nicator, Chandragupta Maurya (c. 305 BCE), the Indo-Greeks and Parthians in the 3rd–2nd century BCE, and the Scythians and the Kushāns from about 100 BCE to 200 CE. Sindh’s population adopted Buddhism under the Kushān rulers in the 1st century CE. From the 3rd to the 7th century CE, the area remained under the rule of the Persian Sāsānids.

The Arab conquest of Sindh in 711 heralded the entry of Islam into the Indian subcontinent. Sindh was part of the administrative province of Al-Sind in the Umayyad and ʿAbbāsid empires from 712 to about 900, with its capital at Al-Manṣūrah, 45 miles (72 km) north of present-day Hyderabad. With the eventual weakening of central authority in the caliphate, the Arab governors of Al-Sindh established their own dynastic rule of the region from the 10th to the 16th century. In the 16th and 17th centuries Sindh was ruled by the Mughals (1591–1700) and then by several independent Sindhian dynasties, the last of which lost the region to the British in 1843. At that time most of Sindh was annexed to the Bombay Presidency. In 1937 Sindh was established as a separate province in British India, but , after Pakistani independence , it was integrated into the province of West Pakistan from 1955 to 1970, at which time it was reestablished as a separate province.

Topographically, Sindh consists of three parallel belts extending from north to south: the Kīrthar Range on the west; , a central alluvial plain bisected by the Indus River; , and an eastern desert belt. The Kīrthar Range is composed of three parallel tiers of ridges, has little soil, and is mostly dry and barren. The fertile central plain constitutes the valley of the Indus River. This plain is about 360 miles (580 km) long and about 20,000 square miles (51,800 square km) in area and gradually slopes downward from north to south. When the river’s annual flood was magnified by unusually heavy monsoon rains in summer 2010, Sindh was hard hit by the ensuing devastation. The eastern desert region includes low dunes and flats in the north, the Achhrro Thar (“White Sand Desert”) to the south, and the Thar Desert in the southeast.

Sindh has a subtropical climate and experiences hot summers and cold winters. Temperatures frequently rise above 115° F (46° C) between May and August, and the average low temperature of 36° F (2° C) occurs in December and January. Annual precipitation averages about 7 inches (180 mm), falling mainly during July and August.

Except for the irrigated Indus River valley, the province is arid and has scant vegetation. The dwarf palm, kher (Acacia rupestris), and lohirro (Tecoma undulata) trees are characteristic of the western hill region. In the central valley, the babul tree is the most dominant and occurs in thick forests along the banks of the Indus. Mango, date palm, banana, guava, and orange are typical fruit-bearing trees cultivated in the Indus valley. The coastal strip and the creeks abound in semiaquatic and aquatic plants.

Sizable and ongoing migration to the province has resulted in an ethnically mixed population. Indigenous groups are the Mehs, or Muhannas, descendants of the ancient Mēds; Sammas and the related Lakhas, Lohānās, Nigamaras, Kahahs, and Channas; Sahtas, Bhattīs, and Thakurs of Rajput origin; Jats and Lorras, both admixtures of the ancient Scythian and the later Baloch peoples; and Jokhia and Burfat. With the advent of Islam in the region in the 8th century, groups of Arab, Persian, and Turkish origin settled in Sindh: the most numerous among these were the Baloch, who, beginning in the 13th century, migrated to Sindh and made it their second homeland after Balochistān. Another great change occurred with the influx of Muslim refugees from India after the partition of the subcontinent in 1947; a substantial part of the population is now descended from refugees from India.

The major indigenous languages in Sindh are Sindhi, Seraiki, and Balochi. With the entry of numerous linguistic groups from India after 1947, other languages have come to be spoken in the urban areas. Of these, the most common is Urdu, followed by Punjabi, Gujarati, and Rajasthani. The national official language, Urdu, is taught in the province’s schools, along with Sindhi. The province’s population is overwhelmingly Muslim.

The population has grown rapidly since 1947 and is concentrated in the cities and the irrigated central valley. The pace of urbanization has also been swift, and two of the largest cities in Pakistan, Karāchi and Hyderabad, are located in the province.

Agriculture is the basis of the economy. Sindh’s agricultural productivity increased substantially after 1961 because of advances in agricultural research, the use of inorganic fertilizers, and the construction of surface drains to relieve waterlogging and salinity in surface soils. Sindh’s largest water project, the Gudu Barrage, provides water for irrigation. Cotton, wheat, rice, sugarcane, corn (maize), millet, and oilseeds are the major crops in the province. There are also many orchards yielding mangoes, dates, bananas, and other fruits. Livestock raising is also important, with cattle, buffalo, sheep, and goats the main animals kept. Sindh’s coastal waters contain prawns and shrimp, pomfrets, shad, and catfish in abundance.

Sindh is one of Pakistan’s most industrialized regions, with much of its large-scale manufacturing centred in Karāchi. The province accounts for a substantial part of the country’s entire raw-cotton production and contains many of the nation’s cotton mills. Several large cement factories turn out much of Pakistan’s cement products, and there is a sugar industry with a large number of mills. There are also plants producing steel and automobiles.

Two major highways, running along the east and west banks of the Indus River respectively, traverse the province from south to north. Karāchi is connected by road and railway to Lahore in Punjab province and to Quetta in Balochistān province. The Indus and some of its channels have served as the main waterways since time immemorial. These waterways are now mainly used for the transport of grain and other agricultural products. Karāchi is Pakistan’s major port.

Karāchi is the stronghold of the national press. Major universities include Sindh University, centred in Hyderabad, and Karāchi University. The Sindhi Adabi (literary) board, which publishes works on Sindhi culture, and the Sindh-Provincial Museum and Library are located in Hyderabad; libraries in Karāchi include the State Bank of Pakistan Library, the Liaquat Memorial Library, and others.Area 54,407 square miles (140,914 square km). Pop. (2006 est.) 35,864,000.